Determining if the pthread_create exist failed with the following output:
Change Dir: /home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_b8167/fast"
make[2]: Entering directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_b8167.dir/build.make CMakeFiles/cmTC_b8167.dir/build
make[3]: Entering directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_b8167.dir/CheckSymbolExists.c.o
/usr/bin/cc   -g -O2 -fdebug-prefix-map=/home/z/libjson-rpc-cpp-0.7.0=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2    -o CMakeFiles/cmTC_b8167.dir/CheckSymbolExists.c.o   -c /home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp/CheckSymbolExists.c
Linking C executable cmTC_b8167
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_b8167.dir/link.txt --verbose=1
/usr/bin/cc -g -O2 -fdebug-prefix-map=/home/z/libjson-rpc-cpp-0.7.0=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2   -Wl,-Bsymbolic-functions -Wl,-z,relro  -rdynamic CMakeFiles/cmTC_b8167.dir/CheckSymbolExists.c.o  -o cmTC_b8167 
/usr/bin/ld: CMakeFiles/cmTC_b8167.dir/CheckSymbolExists.c.o: in function `main':
./obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp/./obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8: undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
make[3]: *** [CMakeFiles/cmTC_b8167.dir/build.make:87: cmTC_b8167] Error 1
make[3]: Leaving directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'
make[2]: *** [Makefile:121: cmTC_b8167/fast] Error 2
make[2]: Leaving directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'

File /home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>

int main(int argc, char** argv)
{
  (void)argv;
#ifndef pthread_create
  return ((int*)(&pthread_create))[argc];
#else
  (void)argc;
  return 0;
#endif
}

Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp

Run Build Command:"/usr/bin/make" "cmTC_13e54/fast"
make[2]: Entering directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'
/usr/bin/make -f CMakeFiles/cmTC_13e54.dir/build.make CMakeFiles/cmTC_13e54.dir/build
make[3]: Entering directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_13e54.dir/CheckFunctionExists.c.o
/usr/bin/cc   -g -O2 -fdebug-prefix-map=/home/z/libjson-rpc-cpp-0.7.0=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -DCHECK_FUNCTION_EXISTS=pthread_create   -o CMakeFiles/cmTC_13e54.dir/CheckFunctionExists.c.o   -c /usr/share/cmake-3.12/Modules/CheckFunctionExists.c
Linking C executable cmTC_13e54
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_13e54.dir/link.txt --verbose=1
/usr/bin/cc -g -O2 -fdebug-prefix-map=/home/z/libjson-rpc-cpp-0.7.0=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -DCHECK_FUNCTION_EXISTS=pthread_create  -Wl,-Bsymbolic-functions -Wl,-z,relro  -rdynamic CMakeFiles/cmTC_13e54.dir/CheckFunctionExists.c.o  -o cmTC_13e54 -lpthreads 
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
make[3]: *** [CMakeFiles/cmTC_13e54.dir/build.make:87: cmTC_13e54] Error 1
make[3]: Leaving directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'
make[2]: *** [Makefile:121: cmTC_13e54/fast] Error 2
make[2]: Leaving directory '/home/z/libjson-rpc-cpp-0.7.0/obj-x86_64-linux-gnu/CMakeFiles/CMakeTmp'


